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Lua templating/Getting started
This page covers some of the absolute basics for developing a simple lua template. Basics Before starting with lua templates, it is important to read up and get to know how to use regular , and preferably read/learn about lua in sites such as Wikibooks as well as reviewing the Lua Reference manual. Workspace Lua templates are stored in the , and all work must always be saved there. For example, a module named helloworld would be stored in Module:Helloworld. Creating a module A module must always contain a table and a line containing a "return " for that table unless it is a meta-module (see below). --Table local p = {} -- code goes here return p For a module to be invoked (or used in a page), it needs to have a function. However, this function must be part of the main table (e.g. invocable): --Table local invocable = {} --can be invoked function invocable.greet(frame) return "Live long and prosper" end -- can't be invoked function askname(frame) return "What's your name?" end return invocable Execution time Lua modules used can only run for a maximum of 10 seconds. This means that modules within a page cannot take longer than 10 seconds to execute, or there will be an error. Copying modules to another wiki Modules hosted here can be used in another wiki, but this may require steps: # Copy the module to your wiki, e.g. Module:Links # Copy all modules it depends on to your wiki. This is a bit complicated because Fandom uses an older scribunto version. But these steps should help: ## Open the module page and find sections that contain text like "require("text"), e.g. in module links text "Dev:Arguments". ## Search for the module in dev.wikia or any other wiki, e.g. Module:Arguments ## Copy this module:arguments to your wiki ## Replace all mentions of require("Dev:") with require("module:"), e.g. require("Module:Arguments") # Redo step two, for every time a require("") is found in copied module. Using input (parameters) Input (or ) can be provided to a module during the invoke. Syntax Once the above code is executed a table (called frame) is created containing all those inputs, and it is passed to a function, and stored in a sub-table called args (e.g. frame.args). For example, using the invoke below will make use of the module: --Module:Invocable --Table local invocable = {} function invocable.greet(frame) local name = frame.args1 or frame.args"name" return "Live long and prosper " ..name end return invocable Output : Live long and prosper john Explanation : Args is a list containing all parameters, args1 refers to the first value, e.g. john, args"name" accesses a named parameter "name". Accessing template input The invoke above cannot be used through a template because the values from a page and a sub-page are kept separate. Those arguments can only be accessed from a template by first retrieving the parent frame or table containing the arguments (i.e. frame:getParent()), and then using the sub-table (frame:getParent().args): Template:Greet: Module:Invocable: --Table local invocable = {} function invocable.greet(frame) local parent = frame:getParent() local name = parent.args1 local name2 = parent.args2 or "" return "Live long and prosper :" ..name ..' '..name2 end return invocable Usage: Output:Live long and prosper : Jack Output:Live long and prosper : Jack Jill Script errors Whenever a module doesn't work properly it triggers a script error in a page. A good explanation of script errors is maintained by WikipediaWikipedia:Lua_error_messages. Advanced An advantage of lua is that it enables one to use external modules and tables that have been created by others. This reduces the need to reinvent the wheel, and more time can actually be spent creating new solutions. Using other modules To use libraries or modules one needs to import that library. This is done using the require method: --Module:Libraries local library = {} function library.greet(frame) local invocable = require("Module:Invocable") return invocable.greet(frame) end return library Output:Live long and prosper Zeus Note: The syntax is case sensitive so "Dev" != "dev". Meta-Modules These are modules that are not meant to be used in a page (e.g. Output: "food & garden" Global modules Modules stored in Dev.wikia.com are called global modules. They work in a similar manner to modules stored in a wiki but can be accessed by any lua module from another wiki (e.g. food.wikia.com). The difference lies only in the syntax (it uses "Dev" instead of "Module") used to obtain the modules: local global_invocable = require("Dev:Invocable") local global_Tables = mw.loadData("Dev:Tables") Tools There are a bunch of useful tools that can help create modules: Code-editor The code-editor (or ace-editor) - this is the default editor that can be disabled as needed. Ace editor in particular comes with a couple of hidden features such as keyboard shortcuts and macroshttps://github.com/ajaxorg/ace/wiki/Default-Keyboard-Shortcuts. Keyboard shortcuts A brief list of some useful shortcuts is shown below: Syntax highlighting and syntax checking The interactive code editor always highlights syntax errors, and sometimes gives helpful information to fix them. Debug console This is a console or terminal that makes it easy to test out code. See also * Lua templating * Lua templating/Debug console * Lua templating/Glossary * Lua templating/Style guide References Getting started